The present invention generally relates to drain valves, and more particularly, to an automatic drain valve having a simplified structure.
Liquid condensate forms in many gaseous fluid handling systems. In order to ensure proper system operation, the condensate is usually separated from the gas (e.g., by gravity) and collected along with solid foreign materials in a reservoir. The accumulated liquid and materials are periodically discharged to prevent the reservoir from becoming too full, causing system backup or reservoir overflow.
Various drain systems have been used to discharge the liquid and foreign materials. One such drain system is described in U.S. Pat. No. 5,983,919, which is incorporated by reference. Typically, the drain system is connected to the reservoir. A float in the system rises and falls in response to the liquid level in the reservoir. When the float rises to a predetermined maximum level, the drain valve opens. In many cases, the float opens a pneumatic valve that permits gas in a float chamber to actuate a drain valve separate from the float chamber to drain the accumulated liquid and foreign materials. Often filtered and dried shop air is used as the pressurized gas.
Many systems have a float chamber mounted between an upper body and a lower body. The upper body has an air inlet and an air outlet separated by a magnetically actuated valve. A float in the float chamber has a magnet that ensures the valve is closed when liquid in the float chamber is below a certain level. When a sufficient amount of liquid enters the float chamber, the float magnet opens the valve, allowing air to travel from the air inlet to the air outlet. External tubing transports the air from the air outlet to a piston mounted in the lower body. The lower body also has passages connecting a liquid inlet to a liquid outlet via the float chamber. The piston controls an external valve mounting in piping connected to the liquid outlet, allowing liquid to pass from the liquid inlet to the piping connected to the liquid outlet.
Thus, it is evident that these prior art systems had housing assemblies with numerous inlets and outlets, a few lengths of external tubing or piping, and a remote liquid valve connected to a piston that were potentially exposed to damage. Accordingly, there is a need for a drain valve that has fewer inlets and outlets, tubing and piping, and remote valve and exposed pistons.